Assembled batteries in which a plurality of battery cells are connected to each other with busbars so that cathodes and anodes thereof are connected in series are known as batteries for electric vehicles, hybrid vehicles, etc. (see, for example, PTL 1). Such an assembled battery is characterized by having high power and high energy density, and in most cases includes lithium-ion batteries as the battery cells. Lithium-ion batteries include positive terminals formed of aluminum (Al) and negative terminals formed of copper (Cu).
Busbars (or bus bars, which are components used to distribute electric energy) are used to connect the terminals of the battery cells to each other. As disclosed in the Problems to be Solved by the Invention section of PTL 2, a busbar may be manufactured by connecting parts of the busbar together by laser beam welding.